Hi, I have been scratching my head for a while on this one…
I have made a TDMA radio that has a simple 4 slot cycle with a relatively low duty cycle (slots are 40% and the remaining 60% of the cycle the USRP is idle). A radio transmits in it’s “owned” slot and receives in all others (3 of them). The transmit is timed as are the receptions in each slot. Transmit is schedule 10 ms in advance (at the start of a cycle) and the receives are scheduled at least 6 ms in advance (at the end of the last receive slot). When I test with a B200mini connected to an Octoclock G for 1 PPS reference, it runs flawlessly for hours (5 is the longest). When, on the exact same Linux host I run with an X310 connected to the same Octoclock G for 1 PPS and 10 MHz, it stops working after not too long with a slew of ’U’s and ’L’s Trying to narrow things down, I created a version fo the radio that only transmits. Reception is completely disabled and I confirm that no receive commands are ever scheduled and rxStreamer->recv() is never called. So, imagine my surprise when after a fairly long time of transmitting successfully (evidenced by using an oscilloscope to view packets), the transmit-only version fails!?! Below is a copy o the log showing the first evidence of failure, namely ’L’s indicating transmits were too late. But, what is the ‘U’ doing there? As I mentioned, no reception functionality is in the program, so what is going on? Anyone else see this kind of thing? I never see it with the B200mini, but see it consistently with the X310. thanks very much for your time and consideration, steven ULLsendFrame() MPDU #719935 mpdu size = 488 bytes at 1518123481s 890000 us ULLLsendFrame() MPDU #719936 mpdu size = 488 bytes at 1518123481s 900000 us ULLLLsendFrame() MPDU #719937 mpdu size = 488 bytes at 1518123481s 910000 us ULLLLLsendFrame() MPDU #719938 mpdu size = 488 bytes at 1518123481s 920000 us ULLLLLLsendFrame() MPDU #719939 mpdu size = 488 bytes at 1518123481s 930000 us ULLLLLLLsendFrame() MPDU #719940 mpdu size = 488 bytes at 1518123481s 940000 us ULLLLLLLLsendFrame() MPDU #719941 mpdu size = 488 bytes at 1518123481s 950000 us ULLLLLLLLLsendFrame() MPDU #719942 mpdu size = 488 bytes at 1518123481s 960000 us ULLLLLLLLLLsendFrame() MPDU #719943 mpdu size = 488 bytes at 1518123481s 970000 us ULLLLLLLLLLLsendFrame() MPDU #719944 mpdu size = 488 bytes at 1518123481s 980000 us ULLLLLLLLLLLLsendFrame() MPDU #719945 mpdu size = 488 bytes at 1518123481s 990000 us ULLLLLLLLLLLLLsendFrame() MPDU #719946 mpdu size = 488 bytes at 1518123482s 0 us ULLLLLLLLLLLLLsendFrame() MPDU #719947 mpdu size = 488 bytes at 1518123482s 10000 us ULLLLLLLLLLLLLLsendFrame() MPDU #719948 mpdu size = 488 bytes at 1518123482s 20000 us ULLLLLLLLLLLLLLLsendFrame() MPDU #719949 mpdu size = 488 bytes at 1518123482s 30000 us ULLLLLLLLLLLLLLLLsendFrame() MPDU #719950 mpdu size = 488 bytes at 1518123482s 40000 us ULLLLLLLLLLLLLLLLLsendFrame() MPDU #719951 mpdu size = 488 bytes at 1518123482s 50000 us ULLLLLLLLLLLLLLLLLLsendFrame() MPDU #719952 mpdu size = 488 bytes at 1518123482s 60000 us ULLLLLLLLLLLLLLLLLLLsendFrame() MPDU #719953 mpdu size = 488 bytes at 1518123482s 70000 us Steven Knudsen, Ph.D., P.Eng. www. techconficio.ca www.linkedin.com/in/knudstevenknudsen All the wires are cut, my friends Live beyond the severed ends. Louis MacNeice
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